mac80211: fix the sparse warnings on endian handling in RANN propagation

The HWMP sequence number of received RANN element is compared to decide whether to be
propagated. The sequence number is required to covert from 32bit little endian data into
CPUs endianness for comparison. The same applies to the RANN metric.

Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>